Accurate network measurement is essential for understanding network behavior and for providing Quality of Service (QoS) guarantees. Most commercial network management software utilizes the Simple Network Management Protocol (SNMP) as the primary method for data collection. Using SNMP involves running SNMP agents on network devices, where an SNMP manager polls these devices for management information.
SNMP-based polling systems have an inherent overhead in terms of processing load on network nodes and network bandwidth consumption. This overhead is further exaggerated when network devices are polled at a high frequency. Such frequent polling is vital for providing QoS guarantees and failure detection. There is a considerable amount of work being done to improve SNMP protocol by reducing the CPU load on the network node. For example, work has been done both to improve SNMP primitives as well as to design better polling strategies by batching SNMP requests. On the other hand, not much research has been done to reduce network bandwidth consumption. Bandwidth is a revenue generating resource and, therefore, service providers are reluctant to allocate large amounts of valuable bandwidth for network management purposes. Thus, bandwidth constraint for network monitoring is an essential design criteria for any measurement infrastructure.
In a centralized measurement system where all network nodes are monitored from a central manager, poll responses are forwarded to a central location in the network. This provides a network-wide view, but creates a potential for bandwidth bottleneck on links that are close to the central manager. On the other hand, in a distributed measurement system the polling load is shared among multiple pollers located at different points in the network. However, using distributed pollers typically increases the cost of network management in terms of the number of pollers deployed, as well as suffers from the lack of a network-wide view.
Accordingly, a method of optimizing a scalable distributed polling system is desirable to reduce the costs of deployment of the measurement infrastructure at an economy of scale.